"When the Messenger of Allah wanted to sleep and he was sexually impure, he would perform ablution as for prayer."  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا أَرَادَ أَنْ يَنَامَ وَهُوَ جُنُبٌ تَوَضَّأَ وُضُوءَهُ لِلصَّلاَةِ  

'Umar bin Khattab said to the Messenger of Allah: "can anyone of us sleep if he is sexually impure?" He said: "Yes, if he performs ablution."  

لِرَسُولِ اللَّهِ ﷺ أَيَرْقُدُ أَحَدُنَا وَهُوَ جُنُبٌ قَالَ نَعَمْ إِذَا تَوَضَّأَ  

He used to become sexually impure at night, then he would want to sleep. The Messenger of Allah told him to perform ablution and then go to sleep.  

أَنْ يَنَامَ فَأَمَرَهُ رَسُولُ اللَّهِ ﷺ أَنْ يَتَوَضَّأَ ثُمَّ يَنَامَ